Bug 14493: export_borrowers.pl - Export patron attributes

Bug 14493: export_borrowers.pl - Export patron attributes

Tweaked Vitor's original patch to accomodate changes to the file.

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export_borrowers.pl changed to support patron attributes

Test plan:

- Use export_borrowers.pl to export all patron and all fields
- The patrons extended attributes are not exported
- Apply the patch
- Use export_borrowers.pl with the no fields specified or with the field patron_attributes
- The patrons extended attributes will be exported in one column

Create by: Vitor Fernandes <vfernandes@keep.pt>
Sponsored by: KEEP SOLUTIONS

Signed-off-by: Jason Etheridge <jason@equinoxinitiative.org>